<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			div{
				border: 10px red solid;
				height: 100px;
				max-width: 500px;
				padding-top: 10px;
				padding-left: 20px;
				box-sizing: border-box;
			}
			
			button{
				height: 50px;
				width: 100px;
				font-size: 24px;
			}
			
			#btn1{
				margin-right: 50px;
				margin-top: 20px;
			}
			
			#btn2{
				margin-left: 50px;
			}
		</style>
	</head>
	<body>
		<div>
			<button id="btn3">按钮3</button>
		</div>
		<button id="btn1">按钮1</button><button id="btn2">按钮3</button>
	</body>
</html>